Climate Science Glossary

Term Lookup

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Term:

Settings

Beginner Intermediate Advanced No DefinitionsDefinition Life:

All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

What relevance does past natural cycles have with recent global warming?

What the science says...

Climate Myth...

It's a 1500 year cycle
“Every one of them [climate records of the past] show this (roughly 1500 year) cycle. It was first discovered in ice cores in Greenland. Then it was seen in ocean sediments in the Atlantic. And now it’s been found everywhere, including in stalagmites in caves. […] it could well account for the current warming.” (Fred Singer)

For someone to state that the global warming we’re experiencing is actually part of a 1500-year natural cycle of global temperature variation is interesting for two reasons. First — in contradiction to the great majority of sceptic arguments that actually deny global warming — this argument requires that the person promoting this explanation must first agree that climate change is, indeed, happening.

Second, they must also refuse to accept the greenhouse effect, a theory first proposed more than 100 years ago and which even many sceptics of the human contribution to climate change, readily accept.

The 1500-year cycle in question has been observed mainly through ice core data as a warming in the northern hemisphere matched at precisely the same time by a cooling in the southern hemisphere. So it’s a heat distribution issue: a global temperature ‘see-saw’ effect. The total heat in the global system remains constant.

In contrast, human-produced global warming has been caused by the rapidly increasing CO2 concentrations in the atmosphere over the last 200 years — rising over 390 parts per million after remaining below 300 parts per million for the previous 800,000 years. And unlike natural heat variations, the current temperature increase caused by CO2 is being recorded occurring all around the globe – on the ground, in the air and in the oceans.

Further viewing

Comments

The evidence that average global temperatures measured for the entire 20th century and to the present actually are a natural cycle with no influence whatsoever from carbon dioxide is shown at http://climaterealists.com/index.php?tid=145&linkbox=true. There is no Anthropogenic Global Warming (AGW) (and therefore no ACC) from added atmospheric carbon dioxide. It is a mistake to believe that there is.

Response: The paper (written by Dan Pangburn) you link to (here's a direct link to the PDF) proposes that just the effects of the Pacific Decadal Oscillation (PDO) and solar activity are sufficient to explain temperature trends over the last 130 years. This argument is fundamentally flawed. Over the past 50 years, the planet has been in positive energy imbalance. Globally, oceans have been accumulating heat.

That is the point. As the paper shows, increased greenhouse gases did not contribute significantly to global warming. The methodology and links to the source data (all measured) are given. Do the exercise yourself and discover that many (not all) Climate Scientists have made an egregeous mistake and a lot of people have been misled.

"In contrast, current global warming is occuring in both hemispheres and particularly throughout the world's oceans, indicating a significant energy imbalance."
The fact remains that in the natural cycle of climate change we are (were?), when the phase of growing - rising - warming in NH - which show modern statistical data ("For smoothing we use local linear regression ...") presented here: http://www.rni.helsinki.fi/research/info/sizer/fig2big.jpg. It’s not Cherry Picking. "Many palaeoclimate records from earth's North Atlantic region depict a millennial-scale oscillation of climate, which during the last glacial period was highlighted by Dansgaard-Oeschger events that regularly recurred at approximately 1,470-year intervals (Rahmstorf, 2003 )."(by Idso K. and C., 2006).

"The 1500 year cycles, known as Dansgaard-Oeschger events, are localized to the northern hemisphere and accompanied with cooling in the southern hemisphere."

NIPCC, skeptics, We draw attention to a hypothetical series of circa 4.2 thousand. years (3 x Bond Events). Impact is stronger here - and the SH is only (weaker) warming; and circa 6 thousand. years solar cycle.
We propose the following scheme for research: warming causes an increase in water vapor content of atmosphere - K.E. Trenberth, J. Fasullo, L. Smith, 2005: Trends and variability in column-integrated atmospheric water vapor. Fig 11. in this paper: here - on the map - we see that the place of the strongest growth of evaporation are related with the strength and reach of the north of THC (vitally affecting the AMO and AO). We know that present not only evaporation but also the strongest warming - it’s in the Arctic. This results in increased emissions of CO2 from the Arctic Sea, but also warming of Tundra: "Lloyd and Taylor (1994) found that the relative sensitivity to temperature change is much greater for soils at LOW temperatures than for warmer soils. For example, in the absence of moisture limitations, an increase from 0 to 1 deg C would result in a 22% increase in respiration, while an increase from 25 to 26 deg C leads to a 5% increase.", "Thus, modest global change scenarios resulting in a 1 to 2 deg C increase in mean temperature would have the most significant effect on the 60 g C/m2 year respired by tundra. [... and in the tundra - c. 1 / 5 land area - where the temperature has risen the most - from 2 to 3 deg C; and soil detritus is a great weight - most of the accumulated 21,6 kg C x m -2 (average) ...] (http://www.biology.duke.edu/bio265/ajm21/intro.html).
At present, oxidation occurs at the age of detritus of several thousand to 10. thousand years. The ratio of carbon isotopes 14/13/12C - so here is similar to the fossil carbon.
We believe that the cyclicality of the climate (in this and the Millennium) have a decisive influence solar cycles - direct; and through its impact on the moon - an indirect (LNC-LNO). We recommend to discuss in particular, the work:
- http://ansatte.hials.no/hy/tide/default.htm,
- Lunar nodal tide effects on variability of sea level, temperature, and salinity in the Faroe-Shetland Channel and the Barents Sea (Yndestad H. at al., 2008);
- The 18.6-year lunar nodal cycle and surface temperature variability in the northeast Pacific (McKinnell, SM , and WR Crawford; 2007 ),
- The impacts of the Luni-Solar oscillation on the Arctic oscillation (Ramos da Silva, R. , and R. Avissar; 2005 ),
- Trends and anomalies in sea-surface temperature, observed over the last 60 years, within the southeastern Bay of Biscay (Goikoetxea N.; 2009),
- Solar Forcing of Changes in Atmospheric Circulation, Earth's Rotation Solar (Mazzarella A.; 2008).

"Changes in solar activity do affect the planet's energy imbalance but over the last 50 years, the sun has showed a slight cooling trend."

The fact is, however, that before the sun was at its highest activity of 8 thousand. years (max - XIX solar cycle) http://www.aanda.org/images/stories/highlight/vol471-1/7704Usos.gif. We also believe that the sun gives its energy through the ocean - with a delay caused by the cycles presented here (solar, LNC: influencing THC - AMO, PDO, EN(LN)SO, NAO, AO, etc.). We believe, that global, hypothetical most probable period of delay is c. half of the Gleissberg cycle. F.e: light cool twenty-first century may be the result of the extended time of local solar minimum weak, from the 60s twenty century (XX solar cycle).

John, I've been reading through Motl's rebuttals to your counterarguments, and I think he does have a point about this one. The title "It's just a natural cycle" implies that the page discusses natural climate cycles in general (including solar cycles, orbital cycles, etc). But your response only deals with the claim that we're experiencing something analogous to a Dansgaard-Oeschger event. Thus the title is a bit of an oversell.

Response: I know, this argument started as a focus on the 1500 year cycle but when I started the Global Warming Links directory, I splintered it off into the more general natural cycle and the more specific 1500 year cycle. But I haven't got around to answering the more general argument. Problem is people have already started adding links to the 1500 year cycle argument so I can't go back to the way it was. Long story short, I painted myself into a corner with my argument structure and the only way out is to find the time to write detailed rebuttals to both. Okay, now where is that time, I know I left it around somewhere...

Can we trust that the ice core data is
collected and interpereted correctly?
Counting those fine lines using a variety
of techniques and extrapolating climate
way back into the past may sound
straightforward to the average laymen
but how much error is there in the graph?
All it takes is a slight shift in the assigned
timeline for one of the ice cores and viola
the bipolar climate becomes global.
Thanks for the video but you will need to
present the graph with links to the source
and a brief explanation of the methods
and reliability of this data. :)

No one seems to be interested in a discussion about the quality of data presented in this video. I would like to add to my above comment that the error in assigning years to layers in any ice core is intrinsically cumulative. If you assume a conservative error estimate of say 1%. That is only 1 in every 100 annual layers is misassigned, then at 50 kyr BP when the most recent of the most striking DO events are suppossed to be taking place you have a +/- 500 year window within which you can align peaks. Given the peaks are so difficult to distinguish in time as they are currently portrayed, what does that tell you about the quality of work in the field of "Climate science"? Even in their current format the two datasets are not opposed but actually aligned at the first DO event at ~90-95kyr BP! But the video is trying to say they are not! Even the trail off from this initial "global" peak is the same in both hemispheres! The further in time we go back from 50kyr the worse (more cumulative) the error. Are there any obvious or striking DO events between 0 and 50 kyr BP? Even at 1% error is there a large enough window to align the supposedly bipolar peaks in this more recent region of time? Are we being too conservative at 1% error? Is "Climate science" really science?

Merely asserting something could be wrong and alleging impropriety doesn't make it so. If you have something of substance that will stand peer review that supports your allegations - bring it on. Or better yet, publish it. I'm sure you'll find many "skeptical" organizations will be glad to provide you with technical copywriters to assist you as well as financial support for your time to do so. Just remember to document your sources and provide links as well...

I also suggest you actually do a little research on the background of paleo temperature records. Here's just one place to start. There are many more.

In the meantime, you're blurring the line between skepticism and denial.

Dr. S Fred Singer should have check his work before spreading it. There is absolutely no empirical evidence that 1,500 year ocean cycle is causing warmining. When was the last time Dr. S Fred Singer published original research in a peer-reviewed journal?

I am having a hard time buying claims that ancient climate cycles do not matter.

The glacial cycle has been rolling along for millions of years, like clockwork, without any CO2 input from mankind. For the past 800,000 years, the glacial cycle has been on a 100,000 year period. We appear to be about 14,000 years into this glacial warming phase. Looking at the graphs of the previous seven warming phases makes this one look pretty similar. It looks to me like most of the global warming we've been seeing is a natural result of the glacial cycle.

A picture of the ice age cycles over the past 800,000 years may make it more obvious that a graph of the ice extent is a repetitive waveform

We reached temperatures 4.5C warmer than today during the previous glacial warming phase, without mankind's CO2 influence. We know that from ice core derived temperature proxy data. So how can you claim that today's global warming is NOT caused by the glacial cycle?

If the current glacial cycle trend is really toward cooling, we ought to be emitting more CO2, and hoping that the AGW believers are right.

None of you seems to realize how rare these warming phases are, nor the devastating effect that the cooling phases of the glacial cycle have had on land based life.

Will human civilization survive the next cooling cycle? Advancing ice will reduce arable land. The cooling climate will result in reduced plant productivity and massive crop failures. It seems that starvation and reduced populations will result. Probably war over surviving arable land. Probably another dark ages. Consider the dramatic impact of the little ice age on human civilization. It was quite devastating.

For an example of what the cooling cycle can do to animal populations, consider the Cheetah. It's genetic inbreeding problems are believed to result from greatly reduced populations during a cooling cycle:

And the sea level then was ..... ?
And the agricultural productivity then was ...... ?
And the human population then was ...... ?

I'm very interested in what the planet can do long before and long after human society was around. I'm much more interested in us doing our best to maintain the best of what we've got.

Has it ever occurred to you that if the climate was warming or cooling for reasons beyond our control, say the sun or global tilt or whatever, that we could then still use our intelligence and our activities to extract or introduce CO2 into the atmosphere to counteract, ameliorate or delay the worst effects?

Another hockey stick graph of CO2 going sky high only means something to AGW believers.

The graphs I was talking about show temperature and ice extent, derived from the ice core.
The temperature graph is what I care about.

AGW believers don't seem to want to admit that the glacial cycle is happening, as it has been happening for millions of years.

We're supposed to believe that the glacial cycle has magically stopped working just because the CO2 level is elevated.

Chris Shaker
Chris Shaker

Response: This thread is inappropriate for the specific topic of impending glaciation that you have focused on. Read the post "We’re heading into an ice age," which answers some of your questions and contentions. If you still have comments, make them on that thread, not this one.

Obviously, you did not catch my remarks about needing to emit MORE CO2 and hope that the AGW believers are right.

You must not have caught the AGW believer's claims that we're supposed to be starting the cooling phase of the glacial cycle. If that is true, and if the AGW theory is true, CUTTING CO2 emissions would be a really dumb idea. Unless you''re actually interested in bringing about the collapse of agriculture and the failure of mankind's civilization, as occured during the dark ages.

Chris Shaker

Response: Please do not use all caps. Use italic, or if you must, bold.

Actually, such a graph means quite a lot, if you understand such measurements.

"We're supposed to believe that the glacial cycle has magically stopped" Who told you that? Open eyes, look at graph. The right-hand edge of the red curve suggests that we might turn colder due to 'natural cycles' sometime in the next 10-20000 years, but if that's what you're planning on, good luck with it.

"In contrast, human-produced global warming has been caused by the rapidly increasing CO2 concentrations in the atmosphere over the last 200 years -- rising over 390 parts per million after remaining below 300 parts per million for the previous 800,000 years."

This is strictly dependant on the proxy that is being used to evaluate the concentration of CO2 in the atmoshphere. Ice cores show one of the largest sensitivities to CO2 whereas Stromata and the B/Ca ratio show much lower sensitivities. Therefore this comment can be easily argued by using Alkenones from Pagini et al. 2005 and 2010 show much higher historic atmospheric CO2 concentrations.

msqrd #25, you've served a double fault here, Pagani shows no such thing. The quoted CO2 concentrations are not strictly dependant on the proxy as you imply, and you missed that Pagani et al 2005 were reconstructing CO2 levels from the mid-Eocene to late Oligocene, some 25-45million years ago. Ice core CO2 measurements go back some 800,000years, so the two ranges do not even nearly overlap.

We used stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores to reconstruct pCO2 fromthe middle Eocene to the late Oligocene (∼45 to 25 million years ago). Our results demonstrate that pCO2 ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during the Oligocene, and reached modern levels by the latest Oligocene. The fall in pCO2 likely allowed for a critical expansion of ice sheets on Antarctica and promoted conditions that forced the onset of terrestrial C4 photosynthesis.

You'll also see how the level of CO2 is implicated in some crucial changes, notably the expansion of Antarctic ice sheets.

You might also want to read Pagani et al, 2010, a paper discussing the Pliocene climate, and see if it supports your conclusions.

You might want to consider what the climate of Earth was like the last time CO2 levels were this high

1500-year cycles...
It is the iceberg armadas (Heinrich events) that show the 1470-year cycle.

The Dangaard-Oschger events are the fast (10yr) cooling and even faster (2-4yr) rewarmings of 10C, several dozen in the last ice age. As Stefan Rahmstorf noted, some coincide with the iceberg armadas, some don't. It is not correct to speak of a D-O Cycle.

The rapidity of the warming is thought to be due to the albedo positive feedback, same thing as is getting started in the Arctic Ocean today but involving the entire North Atlantic Ocean.